FIRST AID FOR THE USMLE TEST PAPER
QUESTIONS AND SOLUTIONS FULLY
UPDATED STUDY PACK
●● Vitamin A (retinol) - Deficiency
Answer: Night blindness (nyctalopia); dry, scaly skin (xerosis cutis);
corneal degeneration (keratomalacia); Bitot spots on conjunctiva;
immunosuppression.
●● Vitamin A (retinol) - Excess
Answer: Acute toxicity—nausea, vomiting, vertigo, and blurred vision.
Chronic toxicity—alopecia, dry skin (eg, scaliness), hepatic toxicity and
enlargement, arthralgias, and pseudotumor cerebri. Teratogenic (cleft
palate, cardiac abnormalities), therefore a ⊝ pregnancy test and two
forms of contraception are required before isotretinoin (vitamin A
derivative) is prescribed.
●● Vitamin A (retinol) - Extra
Answer: Retinol is vitamin A, so think retin-A (used topically for
wrinkles and Acne). Found in liver and leafy vegetables. Use oral
isotretinoin to treat severe cystic acne. Use all-trans retinoic acid to treat
acute promyelocytic leukemia. Isotretinoin is teratogenic.
●● Vitamin B1 (thiamine) - Function
, Answer: In thiamine pyrophosphate (TPP), a cofactor for several
dehydrogenase enzyme reactions: +Pyruvate dehydrogenase (links
glycolysis to TCA cycle) +α-ketoglutarate dehydrogenase (TCA cycle)
+Transketolase (HMP shunt) +Branched-chain ketoacid dehydrogenase
●● Vitamin B1 (thiamine) - Deficiency
Answer: Impaired glucose breakdown p ATP depletion worsened by
glucose infusion; highly aerobic tissues (eg, brain, heart) are affected
first. In alcoholic or malnourished patients, give thiamine before
dextrose to reduce risk of precipitating Wernicke encephalopathy.
Diagnosis made by increase in RBC transketolase activity following
vitamin B1 administration.
●● Vitamin B1 (thiamine) - Extra
Answer: Think ATP: α-ketoglutarate dehydrogenase, Transketolase, and
Pyruvate dehydrogenase. Spell beriberi as Ber1Ber1 to remember
vitamin B1. Wernicke-Korsakoff syndrome —confusion,
ophthalmoplegia, ataxia (classic triad) + confabulation, personality
change, memory loss (permanent). Damage to medial dorsal nucleus of
thalamus, mammillary bodies. Dry beriberi —polyneuritis, symmetrical
muscle wasting. Wet beriberi —high-output cardiac failure (dilated
cardiomyopathy), edema.
●● Vitamin B2 (riboflavin) - Function
Answer: Component of flavins FAD and FMN, used as cofactors in
redox reactions, eg, the succinate dehydrogenase reaction in the TCA
cycle.
QUESTIONS AND SOLUTIONS FULLY
UPDATED STUDY PACK
●● Vitamin A (retinol) - Deficiency
Answer: Night blindness (nyctalopia); dry, scaly skin (xerosis cutis);
corneal degeneration (keratomalacia); Bitot spots on conjunctiva;
immunosuppression.
●● Vitamin A (retinol) - Excess
Answer: Acute toxicity—nausea, vomiting, vertigo, and blurred vision.
Chronic toxicity—alopecia, dry skin (eg, scaliness), hepatic toxicity and
enlargement, arthralgias, and pseudotumor cerebri. Teratogenic (cleft
palate, cardiac abnormalities), therefore a ⊝ pregnancy test and two
forms of contraception are required before isotretinoin (vitamin A
derivative) is prescribed.
●● Vitamin A (retinol) - Extra
Answer: Retinol is vitamin A, so think retin-A (used topically for
wrinkles and Acne). Found in liver and leafy vegetables. Use oral
isotretinoin to treat severe cystic acne. Use all-trans retinoic acid to treat
acute promyelocytic leukemia. Isotretinoin is teratogenic.
●● Vitamin B1 (thiamine) - Function
, Answer: In thiamine pyrophosphate (TPP), a cofactor for several
dehydrogenase enzyme reactions: +Pyruvate dehydrogenase (links
glycolysis to TCA cycle) +α-ketoglutarate dehydrogenase (TCA cycle)
+Transketolase (HMP shunt) +Branched-chain ketoacid dehydrogenase
●● Vitamin B1 (thiamine) - Deficiency
Answer: Impaired glucose breakdown p ATP depletion worsened by
glucose infusion; highly aerobic tissues (eg, brain, heart) are affected
first. In alcoholic or malnourished patients, give thiamine before
dextrose to reduce risk of precipitating Wernicke encephalopathy.
Diagnosis made by increase in RBC transketolase activity following
vitamin B1 administration.
●● Vitamin B1 (thiamine) - Extra
Answer: Think ATP: α-ketoglutarate dehydrogenase, Transketolase, and
Pyruvate dehydrogenase. Spell beriberi as Ber1Ber1 to remember
vitamin B1. Wernicke-Korsakoff syndrome —confusion,
ophthalmoplegia, ataxia (classic triad) + confabulation, personality
change, memory loss (permanent). Damage to medial dorsal nucleus of
thalamus, mammillary bodies. Dry beriberi —polyneuritis, symmetrical
muscle wasting. Wet beriberi —high-output cardiac failure (dilated
cardiomyopathy), edema.
●● Vitamin B2 (riboflavin) - Function
Answer: Component of flavins FAD and FMN, used as cofactors in
redox reactions, eg, the succinate dehydrogenase reaction in the TCA
cycle.
